High speed chain and sprocket transmission



June 13, 1939. B. WELSER I HIGH SPEED CHAIN AND. SFROCKET TRANSMISSION 2 Sheets-Sheet l Filed Feb. 19, 1937 June 13, 1939. B. wELsER HIGH SPEED CHAIN AND SPROCKET TRANSMISSON F'iled Feb. 19, 1957 2' Sheets-Sheet 2 Elma/who@ rinton TVlse Gbtowup Patented June 13, 1.93.9

UNITED STATES HIGH `SPEEI) CHAIN AND SPROCKET TRANSMISSION Application February 19, 1937, Seria1,No. 1l26,698

lclaim.

v Among the uses for which chain and sprocket transmissions or chain drives? are very extensively employed, the driving of the draw-works and associated parts of the well-'known rotary 5 drilling rigs for oil-wells involves very heavyduty service under extremely trying conditions, and the depth of wells thatcan be drilled with over-all economy by these comparatively ,simple and otherwise desirablerigs is largely dependent upon the characteristics of their chain-drives in the combined respects of high speed-capacity, great strength, slow Wear, and capability to operate under poor conditions that tend to cause the chains to jump from their sprockets.

A majorV object of my invention is to provide an improved chain and sprocket transmission better capacitated in 'these respects for welldrilling service, and particularly for the drilling of very deep wells, than any hitherto known chain drive of which I am aware.

f It will be understood that where, in Amost nelds of use of chain and sprocket transmissions wherein pitch length is in excess of 2 inches, chain speeds do not `ordinarily run above 1000 to 1500 ft.' per minute and consistent accuracy in the relative positioning of the driving and 4driven sprockets is expectable, conditions quite normal -to the operation of oilwell drives are far more trying. Expectable variations in the set-up. of the dismantleable oilwell rings often involve slackness in the chains, mis-alignment of their sprockets and running of Achains at steep leaning" angles or even vertically, all of which-as well as occasional quick reversals of chain travel and expectable shocks of sudden-load changestend to cause the chains to jump from their sprockets. And additionally, normal desirable speeds of chain travel Vin these drives are oi the order of 3000 it. per lminute and upward, under which conditions chain breakage or jumping extremely dangerous to the operatorsand to the equipment, of course. v

In these aspects, further, objects that I seek and attain are toprovide in the chainestructure for normal accommodation of heavy loads under the stated high order of speed and notable resistance to galling and quick deterioration of the chains bearings under snap loads andmore protracted overloads, and to provide in the coacting sprockets accommodation for teeth oi' the-proper contour and of adequate height vto substantially minimize likelihood of the chain jumping from itssprocket under the expectably poor conditions of operation referred to.

In long-prevailing` practice it. has been cus- (ci. 'r4-245) -due wearand quick destruction of the chain.

tomary to' use in these well-rig drives, short`I pitch chains of the so-called 3-inch A.P. I.

standard pitch-length in driving the relatively inch pitch drive, a substituted 4-inchpitch drive 10 is subjected to such increase of force of impact of its links against the sprockets and wearing effect upon its cross pins and ass ociated bearing parts that the high speed is accompanied by une In these respects another object of my invention is to provide a. drive'of small-pitch length, f approaching that of the \customary 3-inch standard pitch transmissions, having a load car'- rying strength permitting itsl operation over cus- -20A tomarily-sized sprocket atspeeds of 3000 ft. per.. minute or =upward under loads approximating those for which l1-inch standard pitchv drives have hitherto been commonly' employed, and with wear-capacity .resultant from its construc- 25 tion giving a. greater expectable service liie under maximal speed and load conditions thaneither of the hitherto known short-pitch and longpitch drives just referred to.

As a result of extensive experiments and actual 30 iield tests conducted in an effort tolmeet the unusual and exacting conditions present in these oil rig drives, I have found that the stated objects of my invention may be attained, and with surprising increase in the serviceable life of the 35 drives, where Athe chain-pitch is substantially 3.125 in.. the chain pin diameter is substantially 0.80 in. and the space between the chain rollers is as a minimum substantially 45 per cent. of the pitch-length, while the height or radial length ofV v40 the well-contoured teeth of any 'appropriate-diameter sprocket is suiliciently great to accommodate a very substantial amount of slackness oi chain `without permitting it to jump from the sprockets, such height being desirably about 45 per cent. of the pitch-length.- I have found that such drives operate with surprising length of life at speeds of 3000 vft. per minute-and upward, which require the R. P. M. of the sprocket l(particularly-the smaller 4one in reducing drives) to 50 be of much *higher order than is common in most iields of use of chain drives, wherein maximum R.-P. M. of 'sprockets is limited to a quantity equaling 900 divided by the square root oi the cube of the-pitch in inches, -a formula gener-l elfi' aieaom struction, in which alternate links are more subject to virtual elongation under wear than are the intervening ones.

While one form of my invention has been illustrated and described in precise detail for purposes of clarity of'disclosure, it will be understood that variations from the details described may be made within the spirit of my invention and the scope of the appended claim although. in my experience, variations in pintie land roller` diameter and in eilective pitch-length should be held within limits of of an inch plus or minus of the exemplifying gures hereinbefore stated.

I claim:

A chain and sprocket construction for high speed powei transmissions, in which the presl, each working face of a sprocket tooth being defined by a root curve having a radius approxi- "mately equal to that of-the chainelement engaging therewith', and an entering curve having a radius which bears to the chain pitch substantially the ratio of 0.4' to 1, said vcurves being connected by a plane surface which is substantially perpendicular to the line of pressure.

BRINTON `WELSER. 

